Kidney transplant patients are at increased risk for cancer, likely because of patients' long-term use of immunosuppressive drugs to prevent organ rejection. In this study, Australian researchers examined the incidence of cancer in 481 kidney transplant patients.

The patients had received one of three treatment regimens: azathioprine and prednisolone; cyclosporine monotherapy; or cyclesoporine monotherapy followed by a switch to azathioprine and prednisolone after three months.

In the 20 years after transplant, 226 patients developed at least one cancer, including 48% who developed skin cancer and 27% who developed non-skin cancer. None of the anti-rejection treatments had a greater effect than another on cancer timing or incidence.

The findings indicate that "any differences in cancer risk from these different treatments are unlikely to be clinically significant," said study author Martin Gallagher, of the George Institute for International Health in Australia.

He and his colleagues also found that kidney transplant recipients' increased risk of cancer is significantly influenced by certain characteristics at the time of transplant. For example, non-skin cancer is associated with increasing age and previous smoking history, while skin cancer is associated with increasing age, non-brown eye color, fairer skin, and a functioning transplant.

High-risk patients need to be monitored more closely and use preventive measures to protect against cancer, the researchers said.

The study appears in the April 29 issue of the Journal of the American Society of Nephrology.